1. Field of the Invention
The present invention generally relates to medical devices and methods, and more particularly relates to prosthesis delivery systems used in the treatment of valve insufficiency, such as mitral insufficiency, also referred to as mitral regurgitation.
The heart of vertebrate animals is divided into four chambers, and is equipped with four valves (the mitral, aortic, pulmonary and tricuspid valves) that ensure that blood pumped by the heart flows in a forward direction through the cardiovascular system. The mitral valve of a healthy heart prevents the backflow of blood from the left ventricle into the left atrium of the heart, and comprises two flexible leaflets (anterior and posterior) that close when the left ventricle contracts. The leaflets are attached to a fibrous annulus, and their free edges are tethered by subvalvular chordae tendineae to papillary muscles in the left ventricle to prevent them from prolapsing into the left atrium during the contraction of the left ventricle.
Various cardiac diseases or degenerative changes may cause dysfunction in any of these portions of the mitral valve apparatus, causing the mitral valve to become abnormally narrowed or dilated, or to allow blood to leak (i.e. regurgitate) from the left ventricle back into the left atrium. Any such impairments compromise cardiac sufficiency, and can be debilitating or life threatening.
Numerous surgical methods and devices have accordingly been developed to treat mitral valve dysfunction, including open-heart surgical techniques for replacing, repairing or reshaping the native mitral valve apparatus, and the surgical implantation of various prosthetic devices such as annuloplasty rings to modify the anatomy of the native mitral valve. However, these devices require open heart surgery which requires a lengthy recovery period for the patient and is costly. More recently, less invasive transapical and transcatheter techniques for the delivery of replacement mitral valve assemblies have been developed. In such techniques, a prosthetic valve is generally mounted in a crimped state on the end of a flexible catheter or delivery system and advanced through a blood vessel or the body of the patient until the valve reaches the implantation site. The prosthetic valve is then expanded to its functional size at the site of the defective native valve.
While these devices and methods are promising treatments for valvar insufficiency, they can be difficult to deliver, expensive to manufacture, or may not be indicated for all patients. Additionally some of the delivery systems have large sizes which create large entry wounds in the body. Therefore, it would be desirable to provide improved devices and methods for the treatment of valvar insufficiency such as mitral insufficiency. It would be desirable if such delivery devices had smaller profiles, were easily advanced or steered to the target treatment site, and allowed accurate delivery and deployment of the prosthesis At least some of these objectives will be met by the devices and methods disclosed below.
2. Description of the Background Art
US Patent Publication No. 2015/0342736 describes a prosthetic valve delivery system.